Bundle Branch Reentrant Ventricular Tachycardia Treated with Catheter Ablation in a Patient with Myotonic Dystrophy

BACKGROUND Bundle branch reentrant ventricular tachycardia (BBRVT) is a rarely encountered ventricular tachycardia (VT) and is classically associated with advanced heart diseases. Importantly, the tachycardia is readily curable with catheter ablation. Without suspicion of BBRVT and recording of the His-Purkinje system, it is hard to diagnose accurately. Myotonic dystrophy (MD) is the most common neuromuscular disease in adults and is known to have a risk of development of BBRVT. Here, we report a case of BBRVT in an MD patient with normal cardiac configuration with typical clinical and electrophysiological features. CASE REPORT A 40-year-old man presented with chest discomfort and weakness at the Emergency Department with unstable vital conditions. Electrocardiography showed wide QRS tachycardia with right bundle branch block pattern. The patient had been diagnosed with MD (type I) 3 years ago and had typical clinical features of MD. Transthoracic echocardiography showed normal left ventricular systolic function and no significant structural abnormalities. In the electrophysiologic study, VTs with left and right bundle branch block pattern were induced and diagnosed with BBRVT. Considering the risk of sudden death, implantation of an implantable cardioverter-defibrillator (ICD) was performed. One month later, VT had recurred and was successfully treated with ablation of the right bundle branch. CONCLUSIONS We present a case of 2 different morphologies of BBRVT in a patient with MD and normal ventricular function. Catheter ablation is a curative method for BBRVT and can be a tool for reducing ICD shock.